As the demands for network increase, the standard for communication system is also modified. Hence, the 3rd Generation Partnership Project (3GPP) proposed the mobile communication standard of the next generation, i.e., the 5th generation (5G) mobile communication system. The 5G mobile communication system defines three scenarios for application of communication, including the enhanced mobile broadband (eMBB), the massive machine type communications (mMTC), and the ultra-reliable and low latency communications (URLLC), respectively.
The eMBB, mMTC, and URLLC scenarios have different requirements on the communication system. For example, the eMBB scenario is suitable for a situation with a high user density. Therefore, in response to a large number of needs for transmission rate, a communication device operated under the eMBB scenario requires a larger channel capacity to be assigned to multiple users. The mMTC scenario is suitable for a situation with high demands for machine-type communications, such as the Internet of things (IoT). While a communication device operated under the mMTC scenario is more tolerant for transmission delay, such communication device requires a capability of transmitting small packets at a high efficiency. The URLLC scenario is suitable for a situation requiring a higher reliability and a shorter transmission delay, such as controlling a drone or notifications of urgent events.
In order to meet the requirements for the 5G communication system (in terms of transmission rate and transmission delay, for example), an effective data transmission method has become an issue to work on.